[llvm-branch-commits] [llvm] [BOLT] Deduplicate equal offsets in BAT (PR #76905)

[Amir Ayupov via llvm-branch-commits]

https://github.com/aaupov created https://github.com/llvm/llvm-project/pull/76905

Encode BRANCHENTRY bits as bitmask for deduplicated entries.

Reduces BAT section size:
- large binary: to 11834216 bytes (0.31x original),
- medium binary: to 1565584 bytes (0.26x original),
- small binary: to 336 bytes (0.23x original).

Test Plan: Updated bolt/test/X86/bolt-address-translation.test